Resin products are produced according to purposes such as electric and electronic products, automobiles and building materials. To exhibit performances required according to the purposes, one or several kinds of resins and additives are added to the molded articles. These resins often require high toughness and a modifier for resin is added so as to impart impact strength required to end uses of the resin products.
Usually, this modifier for resin is supplied in the form of a powder. Therefore, dispersion of the modifier into a matrix resin becomes very important element and, when poor dispersion occurs, sufficient modification effect is not obtained and inclusion composed of extraordinary substance of the modifier is formed in appearance. Dispersion of the modifier for resin is particularly important element in electric and electronic components, solder pastes and coating materials. Particularly, it is necessary condition for a modifier for semiconductor sealing material to cause no poor dispersion due to the thinning and fine patterning of a package with recent high degree of functioning and high degree of integration of a semiconductor device.
As a method of imparting the strength to a semiconductor sealing material, a method of adding a rubber such as MBS resin to an epoxy resin has been proposed (see, for example, Patent Documents 1 and 2).    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2000-7890    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. S62-22825